The following table summaries the difference between null and undefined in JavaScript.
| Area | Undefined | Null |
|---|---|---|
| Definition | Undefined means the variable has been declared, but its value has not been assigned. |
Null means an empty value or a blank value. |
| The typeof operator | The typeof() operator returns undefined for an undefined variable. |
The typeof() operator returns the type as an object for a variable whose value is assigned as null. |
| On performing arithmetic operations | It returns NaN on performing arithmetic operations. |
converts to 0 then perform the operation |
| Is it an assignment value? | No, as there is no value assigned to the variable, it becomes undefined. |
Yes, as we assign null to a variable, it is an assignment value. |